General Motors, which has invested close to $3 billion in hydrogen fuel cells (and has been working on them since the legendary Electrovan of 1966), has been quietly working on the technology. By 2020, it will have a fuel-cell car on the road with its partner, Honda, and in the meantime it’s looking at other markets besides automobiles—would you believe submarines?

According to Alan Adler, autonomous and R&D communications at GM, “We will have at least one car in the 2020 time frame, but we’re not racing to big production numbers. While we develop a hydrogen infrastructure, we’re looking at other opportunities for fuel cells as well. We will have a truck we developed for the Army later this year, with an emphasis on stealth operation.”

And then there’s the Navy program. On June 23, GM said it is collaborating with the Office of Naval Research and the Naval Research Laboratory on a plan to use automotive-grade fuel cells in what are known as unmanned undersea vehicles (UUVs), a form of submersible drone.

GM’s fleet of hydrogen-powered Chevrolet Equinox Fuel Cell vehicles, launched in 2007 as part of Project Driveway, have accumulated more than 3 million miles of real-world driving with a fleet of 119-vehicles. (Photo by Steve Fecht for General Motors)

The hydrogen-powered UUV successfully tested (in pools) uses a fuel cell that is basically the same one used in the last generation of Chevrolet Equinox FCV. “That fuel cell is way more durable than we thought,” Adler said. “We have 3.1 million miles of testing, and some of the cars are still out there, and have accumulated more than 120,000 miles.”

According to Frank Herr, Naval Research’s department head for Ocean Battlespace Sensing, “Our in-water experiments with an integrated prototype show that fuel cells can be game changers for autonomous underwater systems. Reliability, high energy and cost effectiveness—all brought to us via GM’s partnering—are particularly important as Navy looks to use UUVs as force multipliers.”

Why not use batteries for UUVs? A critical issue is range, and the Navy is looking for vessels that can be on-mission for more than 60 days. That’s impossible with battery propulsion—the Navy achieves its goals on full-size submarines with nuclear power. “They want longer deployments, and fuel-cells in airtight components give it to them,” Adler said.

The Navy is moving forward with hydrogen and fuel cells on a number of fronts. It has looked at equipping aircraft carriers and other craft with the technology, and in 2012 the Naval Research Laboratory talked about its efforts to extract hydrogen from seawater—a process that also very usefully includes carbon capture. The system, producing renewable hydrogen and capturing carbon, has now been patented, Clean Technica writes.

The new process can be used, with more steps added, to produce liquid jet fuel—with obvious application on carriers. The cost is currently estimated at $3 to $6 a gallon, and the goal is to ramp up how much fuel can be produced.

Making fuel on board has obvious military advantages, including reducing the need for costly at-sea refueling and increasing the time that battle craft could remain on station. The Navy’s Sea Lift Command moved nearly 600 million gallons of fuel to ships at sea in 2015.

For its part, GM will continue to explore where its fuel cells can go—in military and stationary applications, and in cars, too. Charlie Freese, executive director of GM global fuel cell activities, said in a statement, “Our customers will benefit from additional lessons we learn about the performance of fuel cells in non-automotive applications that will be useful in GM’s drive to offer fuel cells across consumer markets.”